We thought a man with a double first from Cambridge and an astonishing start to his acting career would have something interesting and articulate to say about himself. We were right'You know how tennis players raise each other’s game, how Nadal plays his best tennis when he’s up against Federer?

Well, acting with Robert Downey Jr is like playing Agassi. You never know what he’s going to do next. Unless, of course, you happen to be throwing him out of a window and he’s shouting, “Throw me harder, baby. Let’s make it real.”’ Tom Hiddleston shakes his head and laughs. It’s been some journey from the darkness of a cinema in Malmo, Sweden, where four years ago, during a break from filming the first season of Wallander, he spent an evening watching Downey Jr signal his spectacular return to form in the first instalment of Iron Man. Now, in The Avengers, the superhero film to end them all, this charming Old Etonian and Cambridge graduate reprises his role as Loki, the baddie from Thor, and gets to do battle with a line-up of Marvel Comics’ most iconic characters: Iron Man (Downey Jr), the Hulk (Mark Ruffalo), Captain America (Chris Evans) and Black Widow (Scarlett Johansson). But first, back to that evening in 2008. Hiddleston was in Sweden having landed a small part as the sidekick to Kenneth Branagh’s brow-beaten detective.

Up to that point, he’d made a few blink-and-you’ll-miss-it appearances in TV dramas, starred in a small British film and won rave reviews for his stage work, collecting an Olivier Award in the process. ‘I’d been acting for about four years and I’d already seen some of my contemporaries rocketing to immediate and extraordinary levels of success,’ he says, as we sit in the spring sunshine beside a canal in east London.

‘Gemma Arterton, who was two years below me at Rada, was suddenly the great hope of British acting while I was still grinding away in the theatre.

'Eddie Redmayne, who I was at school with, was off making movies with Angelina Jolie and Matt Damon. I thought that if it hasn’t happened for me, maybe it never will.‘We all impose a glass ceiling on our expectations. I’m an eternal realist and the success rate for being an actor is pretty low.

'My father and I used to tussle about me becoming an actor. He’s from strong, Presbyterian Scottish working-class stock, and he used to sit me down and say, “You know, 99 per cent of actors are out of work. You’ve been educated, so why do you want to spend your life pretending to be someone else when you could be your own man?”’Thankfully, Hiddleston stuck to his guns because the last two years have seen an extraordinary turnaround in his fortunes.First, Branagh, who has become something of a mentor, invited him to audition for the title role in Thor, the £95m blockbuster he’d been hired to direct.

Then, in one week, he received a personal letter from Woody Allen asking him to appear in what turned out to be his best film in years, Midnight In Paris, and a phone call from Steven Spielberg, his childhood hero, requesting a meeting about War Horse, the World War I epic that went on to be nominated for six Oscars. From idling in the slipstream of his peers, Hiddleston suddenly emerged as Britain’s hottest young actor, or as Spielberg described him, ‘the new Errol Flynn’. He says he still has to pinch himself, even now.

‘You never get used to it,’ he says. ‘It’s really been amazing and only recently have I been able to have a bit of headspace to sort through the boxes of everything, to process it. It’s been more than I’d ever dreamed of.’ One of three children, Hiddleston spent the first years of his life in south-west London before the family moved to Oxford when his father was offered a job managing Isis, a company that helped university researchers commercialise their intellectual property.

His mother, who works as an arts administrator, took him to the RSC at Stratford and to see arthouse films at the local cinema.

At the age of 13, Hiddleston began as a boarder at Eton. His parents were splitting up at the time.‘I think I started acting because I found being away at school while my parents were divorcing really distressing,’ says the 31-year-old.‘It’s only now I’ve got a retrospective angle on it.

'When you are a teenager, suddenly you start harbouring secrets in a different way.'If you are at a boys’ school, especially, there is a level of bravado that you have to keep up otherwise you’ll get picked on.

'I was really quite upset, and probably very sad and vulnerable and angry. Acting presented a way of expelling those feelings in a safe place.’ Hiddleston heads a golden generation of Old Etonian actors that numbers Eddie Redmayne (My Week With Marilyn, Birdsong), Harry Lloyd (A Game Of Thrones, The Iron Lady) and Harry Hadden-Paton (who recently starred in She Stoops To Conquer at the National Theatre). ‘But I’m wary of labels,’ he says. ‘As an actor, the labels that are so easily attachable to me – like Old Etonian or Cambridge graduate or Rada alumnus – are, in a way, the least interesting things about me. I’ve had to do a lot of work taking off those jackets. The last thing I ever want is to be pigeon-holed.‘I was meeting lots of casting directors and you’d feel the atmosphere change in the room when I said where I went to school. It’s true of everyone in this country; we’re all so much more than we’re allowed to be by this predisposition to keep people in their lane.’Hiddleston is reluctant to dwell on the current vogue for actors educated at posh public schools, and says there are widespread misconceptions about Eton.‘People think it’s just full of braying toffs, who are arrogant and chauvinistic, senseless and ambitious, who are destined to run the country and steal all our money. It isn’t true.

'There are a few people like that but that’s one or two in a school of 1,200. It’s actually one of the most broadminded places I’ve ever been.

'The reason it’s a good school is that it encourages people to find the thing they love and to go for it. They champion the talent of the individual and that’s what’s special about it.’Prince William was one of his contemporaries, and Hiddleston says the fact he was treated like any other boy speaks volumes.

‘There was a general and very quietly stated ethos when he arrived that there was to be no special treatment and no special favours.'It would have made everyone’s life hell if they had to treat him as someone special. I think it was very healthy for him to be just another boy.’It was during his time at Eton that Hiddleston realised that acting was the path he wanted to follow.

‘I did a production of Journey’s End, an RC Sherriff play about World War I, at the Edinburgh Festival. I was 18 and it was the first time that people I knew and loved and respected came up to me after the show and said, “You know, you could really do this if you wanted to.”

'Acting takes such a level of confidence and self-belief and as a teenager I didn’t have that much self-esteem. What teenager does? It was when they started saying I could do it that I really committed to it as a possibility.’

He went on to win a place at Cambridge, where he studied Classics at Pembroke College and quickly established himself as the student actor most likely to succeed, even among contemporaries that included Sir Peter Hall’s daughter Rebecca and his old schoolmate Redmayne.

He was signed by an agent in his first year and managed to combine acting jobs with his studies to the extent that he graduated with a double first.

As well as being personable, Hiddleston is extremely bright and speaks in grammatically perfect paragraphs.
However, he denies his education has equipped him with an extra layer of confidence.
‘I’m always distrustful of inherited confidence and inherited esteem,’ he says.
‘I’ve never wanted to have to transfer the credit for my actions on to anybody else – my parents, my school, my university. I’ve always understood an inherited confidence to be false.’
Later in the conversation, he talks about Britain’s class neurosis and cites his recent nomination for a Rising Star Bafta, for which he lost out to Hackney-born Adam Deacon.
‘It was couched as Eton versus Hackney, and Hackney won. But why can’t Adam just be the more popular actor?

'The one thing I despise is how everything artistic, political or intellectual has to be refracted through this prism of class consciousness. It probably is more sensitive to me but everything becomes really narrow-minded and pedantic and bigoted.’
The big change in Hiddleston’s life took place over a lunch with Branagh in Los Angeles in 2009. As well as Wallander, they had appeared together on stage in a West End production of Checkov’s Ivanov.
‘We really clicked. The two characters we played were locked in an ideological battle of wits. It was like old bull, young bull, and we just went at it every night for 95 shows.’

Branagh was starting work on Thor and surprised Hiddleston by asking him to audition for the title role.

‘Studio executives get nervous about casting new people because the budgets are so big,’ says Hiddleston.
‘No amount of throwing the kitchen sink at them in every audition will ever convince them. You need advocates.’
Hiddleston lost out on Thor to Aussie beefcake Chris Hemsworth but consolation came in his casting as Loki, the scheming brother. He’s in no doubt who he has to thank.

‘Ken has had a life-changing effect. He was able to say to the executives, “Trust me on this, you can cast Tom and he will deliver.” It was massive and it’s completely changed the course of what is available to me to do. Ken gave me my break.’
The film would gross over £280 million but before production had even finished, Hiddleston found himself on the way to another potentially life-changing meeting with Steven Spielberg, for his next film, War Horse.
‘I was telling myself, “You’re about to meet one of your all-time heroes. His films are the reason you’re an actor – ET, Jaws, Indiana Jones, Schindler’s List, Saving Private Ryan... It will be criminal if you pretend to be someone else. To thine own self be true. If it’s supposed to work out, it’ll work out and if it’s not, at least you’ll know you were yourself.”’
The pep talk worked and Hiddleston was offered the part of Captain Nicholls, who rides the horse Joey in a cavalry charge at the beginning of the conflict.

‘It was a massive pinch-me moment,’ he says of his first day of filming, in which he led 120 galloping horses across no-man’s land.

‘As a child, I used to watch Indiana Jones on a loop. For me it was all about Spielberg and Harrison Ford. Then, suddenly, I’m on a horse that I’ve been taught to ride by Vic Armstrong, who was Ford’s stunt double in those films, and Spielberg’s calling “Action!”
‘It was one of the most exciting things I’ve ever done, not just on film but in my life. Balls out, full throttle, there was no acting required. If any of us had fallen off in that charge we would have been trampled underfoot. It’s a hard one to beat as an experience and I got to do it ten or 11 times.’
Having recently put the finishing touches on screen adaptations of Henry IV, Parts 1 and 2, and Henry V, which will be screened as part of the Cultural Olympiad, Hiddleston is currently enjoying a rare period of downtime before heading off around the world to promote The Avengers.

Single after his relationship with the actress Susannah Fielding ended in November, he says he’s had to make painful compromises to get where he has, including missing his best friend’s wedding.
‘It was one of those crazy things where I’d said I’d be there – even if Spielberg called. And Spielberg did call and I wasn’t there. We fell out really badly. It’s OK now. He read me the riot act and then we went out and got slammed.

'Acting just demands everything and if you don’t give it everything, there will be someone behind you who will.’

And the chances are that someone will be a product of Eton’s drama department.